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-   -   Zenith 5311U / 24MC32 restoration (http://www.videokarma.org/showthread.php?t=268586)

bandersen 02-24-2017 11:30 AM

Zenith 5311U / 24MC32 restoration
 
Yes, I finally got myself a roundie courtesy of drh4683! I figured I needed a new color TV to go in my new house :yes:

It's a Zenith model 5311U with a 24MC32 chassis he scored at an estate sale.

He said it does not work (no B+) but the original 21FBP22 tests strong.

It has a vinyl clad metal cabinet and looks to be in very good, all original condition.

Here's are some photos from the ebay listing and it arriving in my garage.

https://c1.staticflickr.com/3/2739/3...f648f12c_c.jpg

https://c1.staticflickr.com/3/2492/3...25591eed_c.jpg

https://c1.staticflickr.com/3/2651/3...77271ae7_c.jpg

https://c1.staticflickr.com/4/3876/3...dfc86d95_c.jpg

https://c1.staticflickr.com/3/2505/3...fd9f8ef5_c.jpg

benman94 02-24-2017 11:39 AM

I was wondering when we'd see you restore a color roundie. Very nice set Bob. :tresbon:

Kevin Kuehn 02-24-2017 12:15 PM

Oh oh. I see a possible new collecting addiction coming on. Good thing you have the bigger house. :D That's a very sharp looking set.

Findm-Keepm 02-24-2017 12:23 PM

Callin Caps, Integrators, Elmenco Tubulars, oh my! I wonder which you will encounter......:D

DavGoodlin 02-24-2017 02:50 PM

Great set there Bob. Put that on a custom dolly and wheel it into your new kitchen. Nothing beats a Zenith color for cartoons over breakfast :D

Electronic M 02-24-2017 04:18 PM

Ahh, so you won that set. That era of zenith, assuming the tuner/IF are good, are real easy to fix and usually rather reliable.

old_coot88 02-24-2017 05:18 PM

The very first thing I would do is verify that the H efficiency coil is intact. The coil form tends to crystalize over time which lets the windings go loose, detuning the coil. If that happens, you can't tune it for the required 'dip' in H output tube cathode current.

The coil form material that's most often affected is whitish, semi-translucent plastic. If the coil form is brown phenolic, yellow, or solid opaque white, it's probably OK.

If the eff. coil is busted it renders the set dead in the water until replaced.

bandersen 02-25-2017 12:01 PM

Thanks for the tip. I dug out this Zenith service manual I've been lugging around since the 80s and found the schematic. Crazy that I've had it for decades and finally have a use for it!

Not sure which is the efficiency coil. Where does it connect in the circuit?

https://flic.kr/p/Sd19Bu

dieseljeep 02-25-2017 12:22 PM

Quote:

Originally Posted by Electronic M (Post 3179326)
Ahh, so you won that set. That era of zenith, assuming the tuner/IF are good, are real easy to fix and usually rather reliable.

I see, some hack left off the X-ray cage around the 6BK4! It also has the GVG tuner. I would've bet it had the Oak or the standard Coil. The base models usually did. It also seems to have a 21FB with a separate safety glass, which is great with me! :thmbsp:

Kevin Kuehn 02-25-2017 05:47 PM

Quote:

Originally Posted by bandersen (Post 3179356)
Thanks for the tip. I dug out this Zenith service manual I've been lugging around since the 80s and found the schematic. Crazy that I've had it for decades and finally have a use for it!

Not sure which is the efficiency coil. Where does it connect in the circuit?

https://flic.kr/p/Sd19Bu

Usually in the plate circuit of the damper tube, but I don't think your chassis has the adjustable coil. I have the same Goodman book and they don't show it on the schematic. If you look at the schematics prior to this chassis they have the coil labeled as such.

old_coot88 02-25-2017 07:00 PM

On Zeniths of this vintage that I've seen, the eff. coil is usually mounted in one of those holes in the rear chassis apron, on the far right end. It's 'snap-in' mounted from inside the apron, with the end of the form protruding out. The slug is adjustable from outside with a 'diddle stick' tool. If this set doesn't have one, I'll hafta add this to my "learn something new every day" list.

On some makes of color TVs the eff. coil is labeled "linearity coil"

EdKozk2 02-26-2017 07:52 PM

Bob, Glad to see you got that set. I bid on it the first time it was auctioned. Seems the previous winning bidder didn't notice the words ' Local Pickup Only ".
I ended up buying a color roundie in Michigan that week. I used to watch BOZO at a friend's house on a 1964 Zenith Roundie.:thmbsp:

zeno 02-26-2017 09:47 PM

Very nice set. Will have an almost unbeatable pix in
a dark room with early content such as Bonanza. I
had one in my bedroom (12X10' !) in the early 70's and
would watch things that sucked just for the realistic color.
Fun to work on too ! You do have to watch the H. eff coil
or you will be buying expensive H outs.......

73 Zeno:smoke:
LFOD !

Tubejunke 02-28-2017 03:01 AM

I have an identical set in appearance, with the exception of the U.H.F. tuner. Also, my chassis must be some other run as what I see around the HV area is configured differently. If I was home I could give my chassis number, but probably not important. My efficiency coil was the first problem I noticed when I got mine and a replacement was almost impossible to find. I finally did get one and was advised to open the cathode of the H.O. tube and insert an ammeter to monitor cathode current and set that coil to something like 200mV. in order to NOT burn up the flyback.
That was a few years back. I wound up having to run the set on a variac at a slightly reduced voltage in order to keep the cathode current where it should be. Probably just leaky caps in the H.O. circuitry. Other than that, the set played well enough and produced a decent enough color picture needing what looks like some dynamic convergence work, which I have never done myself. Frankly, and sadly the set has been put to the side due to the introduction of a woman in the home. LOL! Together we simply just had too much stuff & it was/is in the kitchen surrounded by stuff. No way to pull the chassis and change the caps. Now I actually have my room back, but thus far have no plan of restoration. I’ve regressed back to radio interests and vintage test equipment. Smaller and easier. I may wind up letting it go.
This set Banderson got looks like a very nice set, and although most of the posts here seem to be about RCA sets, these Zeniths are supposedly better built and more reliable. Good luck with the set and don’t burn that flyback!

DavGoodlin 02-28-2017 10:06 AM

The 24MC32 and mid-65's 24NC31 was a departure from the 25MC30 series and earlier roundy zeniths. It was more compact, having the HV cage on top of the chassis rather than beside it.

"learn something new every day" - Old coot, you also never stop seeing new (to you at least) Zenith sets on this forum.


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